Check out System Management > Document Management > External File Reference. What I have done before is open the list of documents (or a subset), go to the List tab, Copy to Excel, do a Find and Replace in Excel, Copy, and do a Paste Update back into the List tab in External File Reference. I believe this form shows the data in the XFileRef table. I realize this isn't using the DMT tool, but maybe this route will work for you.
Greg Bakker
Kooima Company
Greg Bakker
Kooima Company